Over the weekend, I saw that Calder had become very happy after he finished his lunch. Probably because his stomache had been satisfied and also because the family was sitting together, he started bubbling with giggles. And he put his hands over his ears, I believe, erroneously thinking that he could muffle his laughter that way. After he left the table, we started talking about how, if he laughed hysterically, we wouldn't be able to bring him into Malaysia because he would have problem crossing the customs. The next thing we knew, his exuberance had turned into distress. He started crying and biting his finger and knocking his knuckles onto hard objects and wanting to stamp his foot. Ethel observed that he must have heard us talking about him and felt sad that he couldn't go Malaysia (yes, it's a grave mistake to be talking that way about him within his earshot). The next day, she reflected that he's very temperamental, switching his moods so drastically. What I saw, though, was an overflow of emotions - how happiness could become hysteria and sadness become agitation. Perhaps what causes him instability is this overspill of whatever he feels.